Microbiology

1. Microbiology • Antonie van Leeuwenhoek (1632-1723) improved early microscope • Dutch lens maker and scientist • First to view microscopic organisms in drop of water • Spontaneous generation:the idea that living organisms can come from non-living things • Microbiology: the study of microorganisms like viruses, bacteria, archaea, protists, & some fungi • Disease causing microbes are called pathogens.

2. Louis Pasteur • In 1859, Pasteur devised experiment to refute spontaneous generation • In 1884, he proposed the idea of viruses causing disease • Developed some of the first vaccines for rabies • Responsible for pasteurization process

3. Chapter 16: Microbiology • Bacteria and fungi are decomposers • Break down organic & inorganic materials • Some can be used to clean environment (oil spills) • Both bacteria & archaea are prokaryotes • Bacteria have three shapes: rod (bacillus), spherical (coccus), & spiral (spirilli)

4. Anatomy of a Prokaryotic Cell

5. Biology of Bacteria • All have plasma membrane (lipid bilayer) • Most have a cell wall • Contains carbohydrate peptidoglycan • Gram stain is a common test used to identify bacteria • Gram-positive bacteria have cell walls with thick peptidoglycan layer & stain purple • Gram-negative bacteria have thin or lacking peptidoglycan layer & stain pink • Gram-negative bacteria have an outer membrane that contains lipopolysaccharides (LPS) • Released when bacterium is killed by immune system • Triggers inflammation & fever • Some bacteria have a slimy polysaccharide layer called capsule • Protect cell from dehydration & immune system

6. Biology of Bacteria • Motile bacteria have flagella (NEVER cilia) • Fimbriae that bind to specific surface receptors of cells • Most have single circular chromosome located in nucleoid region • Some bacteria form endospores • Thick-walled, dehydrated structures • Capable of surviving extremely harsh conditions • Not for reproduction

7. Bacterial Reproduction • Bacteria can reproduce asexually via binary fission • Each daughter cell is a clone of parent cell • Cell divides with each cell getting a copy of DNA & about half of cytoplasm

8. Bacterial Reproduction • Sexual reproduction does not occur, but there are three forms of genetic recombination: • Conjugation= male cell passes DNA to female cell via a sex pilus 2. Transformation= occurs when bacterium takes up DNA released into environment by dead bacteria 3. Transduction= viruses carrying portions of bacterial DNA from one bacterium to another

9. Bacterial Metabolism • Most bacteria are heterotrophic and must gain nutrients from consuming other organisms • Some are chemoautotrophs • Reduce carbon dioxide to organic compound • Cyanobacteria are capable of photosynthesis

10. Bacterial Diseases in Humans • Streptococcus infections • Cause more disease than any other type of bacterium • Streptococcus pneumoniae causes pneumonia, meningitic, & middle ear infections • Streptococcus mutans cause teeth decay • Streptococcus pyogenes cause mild to severe skin diseases • Tuberculosis • One of leading worldwide causes of death due to infectious disease • Caused by Mycobacterium tuberculosis • Usually infects lungs, but can be found in other areas • Lesions produce tubercles that cause lung tissue to harden • Infects many people who are also infected with HIV

11. Bacterial Diseases in Humans • Food Poisoning • Can cause infection once they enter intestine • Or can produce toxins while they are growing in food • Salmonella causes gastroenteritis after introduced in intestines • Staphylococcus produce toxins in food • Clostridium botulinum produce endospores that survive canning process (possibly most toxic substance on Earth) • Chlamydia Infections • Can cause blindness • Also one of most common sexually transmitted diseases in US • Can cause life-threatening pelvic inflammatory disease (PID) • Antibiotics kill or reduce bacteria by inhibiting protein synthesis or bacterial cell wall biosynthesis

12. Biology of Archaea • More closely related to eukarya than to bacteria • Survive in harsh conditions that are similar to early Earth • Thermoacidophiles= high temperature, low pH like hot springs • Methanogens= anaerobic environments like swamps & animal guts • Halophiles= salty environments such as great salt lakes • Plasma membrane is made up of a monolayer of lipids which helps them resist acid & heat • Cows have large populations of methanogens in digestive tract • Release large amounts of methane gas into environment • Methane gas is a greenhouse gas which contributes to global warming

13. Protists • Domain Eukarya, kingdom Protista • All are eukaryotic, mostly unicellular, microscopic • Capable of sexual or asexual reproduction • Algae can be unicellular, colonial, filamentous or multicellular • Phytoplankton are small, aquatic algae that are photosynthetic • Algae may aquatic (marine or freshwater) or terrestrial (soil, rocks, on trees) • Algae have chloroplasts that contain chlorophyll & sometimes other pigments • Have rigid cell walls made of cellulose • Pyrenoids are organelles that store starch in algae

14. Types of Algae • Green algae • Characteristics that support close relation to plants • Both have cellulose in cell wall 2. Chlorophylls a & b • Storage of reserve food as starch in chloroplast • Examples: Volvox, Chlamydomonas, Spirogyra Volvox Spirogyra

15. Types of Algae cont. • Diatoms • Marine & freshwater • Contain brown pigment • Have shells made of silica • Fossilized remains form diatomaceous earth • Dinoflagellates • Cause red tide & may produce potent toxin • Members of phytoplankton in marine & freshwater • Have protective cellulose plates encrusted with silica • Have 2 flagella that provide whirling motion • Symbiont with coral • May be bioluminescent

16. Types of Algae cont. • Red algae • Mostly multicellular • Contain chlorophyll, red & blue pigments • Some have calcium carbonate in cell wall & help form coral • Produce useful gelling agents • Agar • Carageenan • Porphyra is used as a sushi wrap in Japan Porphyra

17. Types of Algae cont. • Brown algae • Multicellular seaweeds • Contain accessory pigments that range from pale beige to yellow-brown to almost black • Allow absorption of sunlight at deeper depths of ocean • Produces slimy matrix that retains water when tide is out • Algin is used in ice cream, cream cheese, cosmetics • Kelps have blades, stipes, holdfasts similar to leaves, stems, roots of plants

18. Euglena • Freshwater, unicellular organisms • Many have chloroplasts, but some do not • Autotrophic or heterotrophic • Have 2 flagella • Have an eyespot that is photoreceptor for detecting light

19. The Animal-like Protists • Protozoans • Motile, eukaryotic, unicellular • Heterotrophic by ingestion • Grouped according to mode of locomotion • Some are nonmotile • Some move by flagella, cilia, pseudopodia • Distributed in a variety of habitats • May have more than one nucleus • Contractile vacuoles control osmoregulation • Produce cysts that protect them from harsh environements • Promote dispersal to better areas • Have thick cell walls & low metabolic rates • Zooplankton • Found in aquatic environments • Microscopic, suspended organisms that feed on other organisms

20. Ciliates • Largest group of protozoans • All have cilia • Help capture prey • Used to sweep food to mouthparts • Most are freely motile, but some are anchored • Paramecium • Macronucleus= produces mRNA & directs metabolic functions • Micronucleus= involved in sexual reproduction called conjugation • Most protozoans reproduce asexually Paramecium Vorticella

21. Amoeboids • Move by pseudopodia (cytoplasmic streaming) • Aquatic environments • Eat by phagocytosis • Digestion occurs in food vacuole • Entamoeba • Cause amoebic dysentery • Invades intestinal lining & reproduces there • Foraminiferans • A skeleton called a test that covers plasma membrane • Pseudopods push out of test • Can be used to date sedimentary rock • Radiolarians have internal test Radiolarian tests

22. Zooflagellates • Heterotrophic protozoans that use 1 or more flagella • May be parasitic or symbiotic • Trypanosoma brucei • Cause African sleeping sickness • Transmitted by tsetse fly • Attacks blood & causes inflammation decreases blood flow to brain • Trypanosoma cruzi causes Chagas disease • Transmitted by kissing bug • Giardia can cause diarrhea Trypanosoma Giardia

23. Sporozoans • Produce spores • All phases of life cycle are nonmotile except male gametes & zygotes • Either intercellular or extracellular parasites • Plasmodium vivax • Causes malaria • Transmitted by mosquitos • Toxoplasma • Transmitted by cat feces • Can be harmful to fetus

24. Molds as Protists • Water molds & slime molds are protists because both have flagellated cells. • Water molds • Saprotrophic: feed on dead organic matter • Responsible for potato famine in Ireland in 1840s • Filamentous body like fungi, but cell walls composed of cellulose • Flagellated spores produced during asexual reproduction • In sexual reproduction, eggs & sperm are produced • Slime molds • Plasmodial (acellular) slime molds: diploid, multinucleated, cytoplasmic mass enveloped by slime sheath • Creeps along phagocytizing decaying plant material in forest • Cellular slime molds • Exist as individual amoeboid cells • Common in soil where they feed on bacteria & yeasts

25. Fungi • Found in domain Eukarya, kingdom Fungi • Only heterotropic • Release digestive enzymes into external environment • Digest food outside of body • Saprotrophic: decomposes corpses of plants, animals, & microbes • Break down organic nutrients & return inorganic nutrients to producers • Body is composed of a mass of individual filaments called hyphae • The hypha form an interwoven mass called mycelium • Some have septa (cross walls) that separate nuclei • Lack chloroplasts & cell walls are composed of chitin • Are nonmotile & lack flagella

26. Fungi cont. • Use spores to reproduce sexually & asexually • Spores are haploid reproductive cells • Asexual reproduction involves spore developing into new organism without fusing with another cell • Sexual reproduction involves joining of hyphae from two different mating types (+) & (-) to form zygote

27. Zygospore Fungi • Phylum Zygomycota • Mostly saprotrophic, may be parasitic • Ex. Rhizopus stolonifer (black bread mold) • Hypha are specialized • Sporangium: specialized hypha with capsule that produces spores

28. Sac Fungi • Phylum Ascomycota • Named for cuplike reproductive structure called ascocarp • Produce sexual spores called conidia • Ex. Truffles, chestnut blight, Dutch elm disease, Ergot, Penicillium, yeast

29. Club Fungi • Phylum Basidiomycota • Named for their club-shaped sexual reproductive structures called basidia • Most reproduce sexually, but can make asexual spores • Basidia are enclosed in basidiocarp that is formed from (+) & (-) hyphae fusing • Ex. Bracket fungi, puffballs, bird’s nest fungi, stinkhorns

30. Viruses, Viroids, Prions • Viruses are not composed of cells • They are obligate parasites • They can only reproduce inside a living cell • Have no metabolic activity when outside of a cell • Contain nucleic material that directs reproduction once inside host • Contain either RNA or DNA • Have a protein capsid that covers nucleic material • May have a lipid membrane called an envelope that surrounds capsid • Viroids are strands of RNA that can reproduce inside of a cell. • Prions are protein molecules that cause other proteins to become prions.

31. Life Cycle of Typical Animal Virus